The proposed study is designed to determine how distinct subsets of melanocyte stem cells (MSCs) we have identified are regulated and maintained in the stem cell state and contribute to neural crest-derived cell regeneration. The rationale for the study is based upon our discovery that MSCs not only populate a region of the murine hair follicle (HF) termed the bulge, also the site of keratinocyte stem cells (KcSCs) of the HF, but also the secondary hair germ (SHG), a transient structure at the base of the telogen, or resting, HF adjacent to the dermal papilla. Our laboratory has developed methods to separate and study these two cell subsets in the viable state using a combination of a unique transgenic mouse system and fluorescence-activated cell sorting (FACS).The objectives of our studies are to discover specific markers of these stem cell subsets and to determine whether CD34+ MSCs in mice, and their cellular analogs in humans, can regenerate functional glial and neuronal cells, as suggested by preliminary data. We will also determine both in vitro and in vivo whether the CD34+ MSC subset, which exhibits an expanded developmental potential compared to CD34- MSCs, can regenerate neural crest- derived glial and neuronal cells. Information obtained from murine experiments will be used to identify comparable stem cell populations from human skin. These studies will be accomplished a unique, bitransgenic mouse line we have developed, Dct-H2BGFPki, in combination with the FACS facility and other core resources associated with my research laboratory located in the Department of Biochemistry and Molecular Biology at the University of Maryland School of Medicine. The results of these studies should have a positive impact on the health care of Veterans. Our discovery that the CD34+ MSC subset selectively expresses glial and neuronal markers may provide a strategy for using cells easily obtained from human skin to be used to support Veteran recovery from neurological injury and neurodegenerative disease.